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Fuel pumps, TPI vs MPI vs?

JnJ

NAXJA Forum User
Location
San Antonio TX
Ok, the Haynes manual I have states that there are two different electronic fuel pumps, one for MPI and one for TPI. I believe the TPI was used on the 2.8s and 4 cyl. I know my 87 XJ 4.0 uses MPI, all Jeep 4.0s do. I have a used parts dealer saying that he has pumps for 87 - 90 4.0 and 91+ HO 4.0, is there a difference between the HO and Non-HO 4.0 fuel pumps.
 
Last edited:
JnJ said:
Ok, the Haynes manual I have states that there are two different electronic fuel pumps, one for MPI and one for TPI. I believe the TPI was used on the 2.8s and 4 cyl. I know my 87 XJ 4.0 uses MPI, all Jeep 4.0s do. I have a used parts dealer saying that he has pumps for 87 - 90 4.0 and 91+ HO 4.0, is there a difference between the HO and Non-HO 4.0 fuel pumps.


It doesn't look like it. I looked it up here at work and the info tells me that the PUMP is the same from 87-93 wether 4.0 or 2.5...however the sending unit MAY vary.
 
96 and later pumps had the pressure regulator mounted on the pump in the tank.
I don't know if they interchange even with some mods.
I had an 86 2.5 TBI xj that had 16 psi at the TB. My 96 xj 4.0 engine (in a CJ) holds 30 + psi so I doubt the pumps are the same.
 
I'll clarify, I'm talking about the pump and sending units. Basically is there a difference between different model years with the 4.0? This guy is saying that the 87-90 4.0 uses a different unit then the 91+ 4.0. The manual I have only specifies a difference between TBI and MPI, and all 4.0s are MPI.
 
JnJ, the pumps will work in either application but if you swap one version for the other your fuel gauge will work backwards.
 
JnJ said:
Your saying the TPI and MPI can be interchanged?

The TPI pump pressure would be too low for the MPI system. Sorry, I was talking about the 2 different 4.0 pump assemblies for the MPI. I will be changing out the weak pump soon in my 93 XJ with the unit from my 89 XJ (it works fine and I'm cheap) and I hope I can just use the pump itself without changing the sender since I know it will be reversed.
 
So, do you know at what model year the MPI pumps/sending units changed? If I posted pictures would you know which is which?
 
IIRC, the Renix system (87-90) and the Chrysler MPI (91-95 only) pump can be swapped but the fuel gauge senders work reversed from each other. From 96 up it's a different pump, regulator, return system, sender and tank. Someone correct me if I'm wrong.
 
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